Do you really know what’s in your go-to olive oil? And what about that favorite coffee blend? You may be scratching your head. “Um, olives and, well, coffee beans, obviously.” Not so fast.

Foods we eat every day are packed with things that aren’t supposed to be there—a practice known as “food fraud”—according to a recent report from the United States Pharmacopeial Convention and their website FoodFraud.org. In order to reduce costs, unscrupulous companies illegally cut a primary ingredient with something less expensive. And the top 11 most frequently adulterated foods are things many of us eat every single day.

We do so unwittingly because the impostor ingredients are very hard—if not impossible—for the consumer (that would be you) to detect. “That’s the real challenge for the experts and agencies to detect food fraud: Consumers don’t often notice a quality problem, and the contaminants are unconventional,” says Michigan State University’s John Spink , PhD, associate director of their Anti-Counterfeiting and Product Protection Program. They’re not typically found in food products, so most of the adulterants go unnoticed. And though adulterants are usually not dangerous, they can be—like when dog food laced with melamine started killing dogs.

But don’t panic yet. “The prevalence of food fraud is ultimately very low,” Spink says. Spink’s tips for steering clear of food fraud? Find a retailer you trust to stock healthy, safe products, and if you get sick, report any food poisoning immediately to your county board of health. Now read on for the 11 most fraudulent foods.

We’d be hard-pressed to find another oil so healthy as that from olives. In all of its various virginities, olive oil lowers cholesterol, knocks out stomach bugs, and even makes skin glow. But that’s not the whole story. Researchers found that olive oil—yes, even the extra-virgin kind—is the most adulterated food, usually cut by hazelnut oil. (Sound good to any nut-allergy sufferers out there?) Other imposter ingredients include corn oil, sunflower oil, peanut oil, vegetable oil, soybean oil, palm oil, and walnut oil.

If you think that milk in your coffee comes from a cow, you might be mistaken. Turns out, there may be a veritable zoo of producers in your carton. Sheep's milk has been found to be cut with bovine milk, and buffalo milk with goat-antelope milk. Milk was also adulterated with reconstituted milk powder, urea, and rennet. But wait, there’s more! Milk was even cut with something called “fake milk”: oil, urea, detergent, caustic soda, sugar, salt, and skim milk powder. We’re not sure that does a body good…

Honey is one of our main squeezes for its healing antioxidants and downright deliciousness. But it’s also one of the most common fraudsters. You may also find sugar syrup, corn syrup, fructose, glucose, high-fructose corn syrup, beet sugar, and “honey from a non-authentic geographic origin” in that bottle—rendering it what we’ll call not-honey. Some honey is also likely laced with illegal Chinese antibiotics from abroad and heavy metals, according to Food Safety News.

Saffron is the world’s most expensive spice , so its place on this list shouldn’t come as a surprise. What is a surprise is all the stuff sometimes mixed with it. Inside those tiny, astronomically priced bottles of saffron, scientists have found glycerin, sandalwood dust, tartrazine (a yellow dye linked to hyperactivity in children and lupus); barium sulfate (a fluid mainly used in oil well drilling); and borax.

Orange juice is no stranger to repulsive adulterants like illegal fungicide, and now, here are a few more reasons not to trust anything you don’t squeeze from the fruit: OJ has been shown to host unlisted lemon juice, mandarin juice, grapefruit juice, high fructose corn syrup, paprika extract, and beet sugar as some of its uninvited guests.

Nothing starts a morning right like a fresh-brewed cup of…twigs? Believe it or not, researchers have found them in coffee, along with roasted corn, ground roasted barley, and even roasted ground parchment. Adulterants in instant coffee are every bit as sneaky; they include chicory, cereals, caramel, more parchment, starch, malt, and figs.

In December 2012, the conservation group Oceana found that 39% of seafood samples bought in New York City were actually mislabeled as a different species. The fake fish phenomenon is apparent in records, too. The US Pharmacopeial Convention found that fish labeled "white tuna" and "butterfish" are often a fish called escolar, which is banned in Italy and Japan for its waxy esters, which may cause food poisoning. Benign-sounding "monkfish" is even sometimes a disguise for puffer fish, which has caused tetrodotoxin poisonings in the US, the group said.

That glass of fruit juice might look fresh-squeezed, but chances are, it isn't. Fraudulent replacements for palm oil and other acceptable food ingredients are rampant: The US Pharmacopeial Convention found 877 food products from 315 companies with fake clouding agents. What's the most common fraudster? Meet the plasticizer Di(2-ethylhexyl) phthalate (DEHP), a chemical that's been linked with cancer and thwarted reproductive development in children, the group says.